Fracture properties of concrete containing recycled concrete aggregates

Abstract

Six different concrete mixtures were cast in the laboratory to evaluate the fracture behaviour of paving concrete made with recycled concrete as a coarse aggregate, virgin coarse aggregate, and a blend of recycled concrete and virgin coarse aggregate. Discrete structural fibres were also added to each concrete mixture to compare with the fracture behaviour of the plain concrete mixtures. Single-edge notched beam, compression, and split-tensile tests were performed. For the specific recycled coarse aggregate (RCA) and virgin aggregate types studied, the total fracture energy of an RCA concrete mixture was improved by 53% by blending it with virgin coarse aggregate. The fracture behaviour of RCA concrete with 0·2% volume fraction of synthetic macrofibres was also similar to the same fibre dosage level with virgin and blended coarse aggregate concrete. In order to achieve the same tensile strength and fracture properties as virgin coarse aggregate concrete, RCA concrete mixtures must be modified by blending them with virgin coarse aggregates or adding discrete structural fibres.